Axial and shear fracture strength evaluation of silicon microneedles

作者：Khanna Puneet^*; Luongo Kevin; Strom Joel A; Bhansali Shekhar

来源：Microsystem Technologies, 2010, 16(6): 973-978.

DOI：10.1007/s00542-010-1070-4

This research aims to quantify fracture limits of hollow silicon microneedles due to axial and shear forces, and validate their use on human skin. Needle failure due to axial and shear loads may be due to heterogeneous peak stresses within the bulk material. Analytical determination of physical usage limits of microneedles can be misleading, as beam fracture models do not translate well to the micro-scale. In this research, various sizes of hollow silicon microneedles were fabricated. Their point of failure due to fracture was tested via application of axial and shear forces. Axial fracture of 36 gauge silicon microneedles took place at about 740 gram-force. It was determined that the axial force experienced by microneedles during insertion into human cadaver skin, is much lower than this critical limit, and thus needle failure due to breakage can thus be generally attributed to shear forces. Fracture limits of microneedles due to shear forces were quantified; ranging from about 36 gram-force for 36 gauge needles to about 275 gram-force for 33 gauge needles.

• 出版日期2010-6